This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primary motivation of this project is to quantify the DNA quantity within a live cell without adding any extra agent. The refractive index of DNA has not been accurately measured near the ultraviolet range, but the reported absorption spectra suggest it has different dispersion characteristics from proteins. Hence, by measuring the refractive index map of a live cell at two or more different wavelengths, we expect to quantify three dimensional distribution of DNA within a live cell.